What is the diff. between 3.8 and 3.9 as far as exhaust? I looked up cat back and a few others and they don't show a 3.9. I have an 04 v6 5speed with 3.9L will the 3.8 fit the same?

 

Tim-

I don't think there is a difference. I read a story in one of the Mustang Magazines a while back about the 3.9's slipping into the '04's, or the confusion associated with the differences. (There might even be a Thread floating around on this site.) The differences should not negate your cat-back selection. And I don't even think it would make a difference with headers. The best advice is to ask the supplier/manufacturer before ordering if you are still unsure.

And Hello and Welcome!

 

only differance is the crank a little bit in the rods and pistons and thats it and they're very very minor at that...exhaust, intake manifold ect ect ect are all the same theres no hp differance 3.8 parts will work on a 3.9 with no problem wether they're bolt on or rear gears